Simple Example showing CVE-2021-44228 in action

Explanation

• To reproduce this issue, I am removing the transitive dependency for logging from SpringBoot.
• Instead, I am bringing in spring-boot-starter-log4j2
• spring-boot-starter-log4j2 brings in log4j-core which has the remote code exploit (RCE) vulnerability.

Running API

• Either run the command ./gradlew clean build bootRun in a terminal OR
• Right click and click run in Log4TestApplication.java.

What happens when you pass in the JNDI value?

• Because we are resolving to a non-existent site, we get a ConnectException.
• But, imagine the possibilities if this was an actual malicious server!

Possible fix?

• IF YOU ARE USING MAVEN - https://github.com/strawhatasif/log4j-test/tree/maven-variant
• Located in the https://github.com/strawhatasif/log4j-test/tree/strategic-fix.

References:

• https://www.lunasec.io/docs/blog/log4j-zero-day/
• https://www.bleepingcomputer.com/news/security/new-zero-day-exploit-for-log4j-java-library-is-an-enterprise-nightmare/
• https://www.fastly.com/blog/digging-deeper-into-log4shell-0day-rce-exploit-found-in-log4j